Adjustable dumbbell



FIG. 1 is a perspective view of the adjustable dumbbell of the present invention;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for an adjustable dumbbell, as shown and described. 